CHAPTER 4 IMAGE FORMATION SYSTEM
4–18
COPYRIGHT
©
1998 CANON INC. CANON NP7161/NP7160 REV.0 AUG. 1998 PRINTED IN JAPAN (IMPRIME AU JAPON)
Figure 4-206
DC controller
PCB
Reference
voltage
circuit
TNFDT
Power
supply
PCB
HVT
J106
-9
+5V
J303
-1
-2
-3
J301
-1
J210
-10
J212
-16
Waste toner sensor
(light-emitting unit)
Waste toner box
Waste toner sensor
(light-receiving unit)
Light-blocking plate
Stopper
Comparator
circuit
D. Monitoring the Waste Toner Box
The copier monitors the waste toner box in two levels.
The amount of waste toner inside the waste toner box is checked by the waste toner sensor.
The waste toner sensor is a pair of photosensors (light-emitting cell and light-receiving cell), and
is designed to generate the waste toner full detection signal (TNFDT) when waste toner blocks
the light between the two photosensors.
The DC controller PCB monitors the state of the waste toner sensor at all times; when the
voltage of the waste toner full detection signal (TNFDT) drops below the reference voltage, it
will identify the condition as “pre-waste toner full condition” and will flash the Waste Toner
indicator on the control panel.
When the waste toner box is not set, the light-blocking plate blocks the light between the
photosensors, causing the copier to flash the Waste Toner indicator.